Acoustic performance is an important product differentiator among communication devices. A communication device, such as a portable radiotelephone, employs a speaker to convert electrical signals into sound waves in the human-audible frequency range of 20 Hertz (Hz) to 20,000 kilo-Hertz (kHz). When positioned against the user's ear during operation, the speaker enables a user of the radiotelephone to hear a representation of a caller's voice, as well as other sounds such as dial tones.
In addition to the traditional operation where the communication device is held close to a user's ear, the newer generation of communication devices offers hands-free speakerphone operation. Further, most communication devices also employ an alert transducer for audible notification of various operations including incoming messages, alarms, and the like.
A variety of techniques have been developed to detect whether the communication device is operating in a close-talking mode, speakerphone mode, or audible alert mode. In one technique, for example, a host processor keeps track of the current operating mode of the device based on user selection. If a user selects the speakerphone option, then the host processor sets a number of device parameters such as echo cancellation thresholds, microphone sensitivity and high audio speaker output level to optimize the performance of the device in that mode. Another technique for detecting whether the communication device is operating in a close-talking, speakerphone mode, or audible alert mode utilizes the outputs of gravitational sensors. According to this technique, the processor not only keeps track of the current mode, but will also switch from one operating mode to the other based on the output from the gravitational sensors.
It is desirable to use the same speaker for the earpiece audible operation, the speakerphone operation, and the alert operation in order to minimize cost and size of the communication device. One problem with such multiple-utilizations is that the alert and/or speakerphone audio level at the earpiece during close talking would tend to exceed a typical person's required limit for comfort or safety.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.